CVD apparatus and CVD method

ABSTRACT

The present invention provides a CVD apparatus and a CVD method for use in forming an Al/Cu multilayered film. The Al/Cu multilayered film is formed in the CVD apparatus comprising a chamber for placing a semiconductor wafer W, a susceptor for mounting the semiconductor wafer W thereon, an Al raw material supply system for introducing a gasified Al raw material into the chamber and a Cu raw material supply system for introducing a gasified Cu raw material into the chamber. The Al/Cu multilayered film is formed by repeating a series of steps consisting of introducing the Al raw material gas into the chamber, depositing the Al film on the semiconductor wafer W by a CVD method, followed by generating a plasma in the chamber in which the Cu raw material gas has been introduced and depositing the Cu film on the semiconductor wafer W by a CVD method. The Al/Cu multilayered film thus obtained is subjected to a heating treatment (annealing), thereby forming a desired Al/Cu multilayered film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a CVD (chemical Vapor Deposition)apparatus and a CVD method, and more particularly, a CVD apparatus and aCVD method for forming an Al/Cu multilayered film.

2. Description of the Background

In a semiconductor device, wiring (e.g., metal) is generally formed on adevice formation region on a silicon semiconductor wafer by, forexample, etching an Al--Cu film formed by sputtering using an Al--0.5 wt% Cutarget.

Recently, with the trend toward high integration of the semiconductordevice, it has been desired to reduce the wiring width. However, it isdifficult for a hitherto-used sputtering method to form a fine wiringwhich will be required by a design rule in future.

Then, as a technique replaceable for the sputtering method, a CVD methodhas been studied. Since the CVD method includes a vapor deposition step,a film is easily formed on a complicated substrate surface and minuteportions such as portions having a large aspect ratio and contact holes.

However, it is difficult to form the Al--Cu film suitable for wiring bythe CVD method.

To form the Al--Cu film, conventionally employed is a method in which aCu component is added to an Al film (CVD) formed by the CVD method. Inthe conventional method, the Cu component is diffused into the Al film(CVD) by depositing an Al--Cu film or a Cu film on the Al film (CVD) bysputtering and annealing the obtained film.

The Al--Cu film of this type is reported in "Symposium on VLSItechnology Digest of Technical Papers (1996), p42".

In the case where the Cu component is dispersed into the Al film (CVD)by use of a single wafer process system having a multichamber type, twoprocess chambers are required; one is to form the Al film by the CVDmethod and the other is to form the Al--Cu film or the Cu film bysputtering. However, film-formation has to be performed two times bytransporting a single wafer between two process chambers. As a result,the throughput thereof inevitably decreases.

To overcome the decrease in throughput, if a plurality of chambers areprepared for each of the Al-film formation and Al--Cu film or the Cufilm formation, the entire apparatus becomes quite large, raising amanufacturing cost.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a CVD apparatus and aCVD method capable of obtaining an Al/Cu multilayered film with a highthroughput but without increasing the size of the apparatus.

The present invention provides a CVD (chemical vapor deposition)apparatus comprising:

a chamber capable of maintaining vacuum conditions having an exhaustingsystem;

a susceptor disposed in the chamber, for mounting an object to beprocessed;

an Al raw material supply system having a first passage for introducinga gasified Al raw material into the chamber, for forming an Al film;

a Cu raw material supply system having a second passage for introducinga gasified Cu raw material into the chamber, for forming a Cu film, thefirst passage being independent of the second passage; and

exhausting means for vacuum-exhausting a gas including the gasified rawmaterial introduced into the chamber;

wherein the Al film (formed of the Al raw material gas) and the Cu film(formed of the Cu raw material gas) are alternately stacked one upon theother by chemical vapor deposition (CVD) on a surface of the object tobe processed by introducing the Al raw material gas or the Cu rawmaterial gas alternately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a schematic structure of a CVD apparatusaccording to an embodiment of the present invention.

FIG. 2 is a view showing an Al raw material supply system for supplyingAl gas into the CVD apparatus shown in FIG. 1.

FIG. 3 is a view showing a Cu raw material supply system for supplyingCu gas into the CVD apparatus shown in FIG. 1.

FIG. 4 is a view showing a modified example of the Cu raw materialsupply system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Al raw material supply system of the CVD apparatus comprises an Alraw material supply line for supplying an Al raw material. The Al rawmaterial supply line includes:

Al raw material gas generating means for generating a predeterminedamount of an Al raw material gas from a liquid-state Al raw materialcontained in a vessel by bubbling with a predetermined carrier gas ordirect gasification;

Al gas bypass means for either supplying the generated Al raw materialgas to the Al raw material supply system or exhausting the generated Alraw material gas outside using the exhausting means by switch operationof a valve;

first gas purge means for purging a remaining gas in the chamber or in agas pipe by supplying a predetermined carrier gas either from the Al rawmaterial gas supply line to the chamber or from the Al raw materialsupply line to the Al raw material gas bypass means; and

Al raw material switching means for switching either between the Al rawmaterial gas bypass means and the Al raw material supply line or betweenthe first gas purge means and the Al raw material supply line.

The Cu raw material supply system comprises a Cu raw material supplyline for supplying a Cu raw material.

The Cu raw material supply line includes

Cu raw material gas generating means for generating a predeterminedamount of a Cu raw material gas gasified by heating a solid-state Cu rawmaterial contained in a vessel with the aid of a predetermined carriergas;

Cu gas bypass means for either supplying the generated Cu raw materialgas to the Cu raw material supply system or exhausting the generated Curaw material gas outside using the exhausting means by switch operationof a valve;

second gas purge means for purging a remaining gas in the chamber or ina gas pipe by supplying a predetermined carrier gas either from the Curaw material gas supply line to the chamber or from the Cu raw materialsupply line to the Cu raw material gas bypass means; and

Cu raw material switching means for switching either between the Cu rawmaterial gas bypass means and the Cu raw material supply line or betweenthe second gas purge means and the Cu raw material supply line.

The present invention further provides a CVD method of forming a filmfrom the raw material on a surface of an object to be processed which isplaced in an atmosphere mainly consisting of a predetermined rawmaterial gas. The CVD method comprises:

a multilayered film formation step for forming an Al/Cu multilayeredfilm by repeating, predetermined times, Al film formation for forming anAl film on a surface of the object to be processed by introducing agasified Al raw material (Al raw material gas) into the atmosphere andCu film formation for forming a Cu film on a surface of the object to beprocessed by introducing a gasified Cu raw material (Cu raw materialgas) into the atmosphere, thereby forming an Al/Cu multilayered film inwhich the Al film and the Cu film are stacked alternately on the objectto be processed surface; and

a heat treatment step for annealing the Al/Cu multilayered film underpredetermined conditions, thereby forming a desired Al/Cu alloy film inwhich diffusion between the Al film and the Cu film takes place.

As mentioned in the foregoing, the present invention provides a CVDapparatus and a CVD method for use in forming an Al/Cu multilayeredfilm. The Al/Cu multilayered film is formed in the CVD apparatuscomprising a chamber for placing an object to be processed, a susceptorfor mounting the object to be processed thereon, an Al raw materialsupply system for introducing a gasified Al raw material into thechamber and a Cu raw material supply system for introducing a gasifiedCu raw material into the chamber. The Al/Cu multilayered film is formedby repeating a series of steps consisting of introducing the Al rawmaterial gas into the chamber, depositing the Al film on the object tobe processed by a CVD method, followed by introducing the Cu rawmaterial gas into the chamber and depositing the Cu film on the objectto be processed by a CVD method. The Al/Cu multilayered film thusobtained is subjected to a heating treatment (annealing), therebyforming a desired Al/Cu multilayered film.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinbefore.

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a view showing a schematic structure of a CVD apparatusaccording to an embodiment of the present invention;

FIG. 2 is a view showing an Al raw material supply system for supplyingAl gas into the CVD apparatus shown in FIG. 1;

FIG. 3 is a view showing a Cu raw material supply system for supplyingCu gas into the CVD apparatus shown in FIG. 1; and

FIG. 4 is a view showing an modified example of the Cu raw materialsupply system.

Now, embodiments of the present invention will be described withreference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing a structure of theCVD apparatus according to the present invention.

The CVD apparatus has a chamber 1 formed of aluminium so as to maintaina vacuum state. In the chamber 1, a susceptor 2 is fixed by a supportingmember 3 which is immobilized on the bottom portion lb of the chamber 1.The susceptor 2 is responsible for holding a (object to be processed)such as a semiconductor wafer W horizontally.

A guide ring 4 is arranged in the outer periphery of the susceptor 2,for guiding the semiconductor wafer W to fit in a holding position whilecovering the susceptor to prevent an extra film from being deposited.

A heater 5 is embedded inside the susceptor 2. The heater 5 applies heatto the semiconductor wafer W held by the susceptor 2, upon supplyingpower from the power source 6, thereby raising temperature to a desiredvalue. The temperature of the heater 5 is controlled by a controller 7via the power source 6 in accordance with a signal sent from atemperature sensor (not shown).

An exhausting port 8 is formed in the bottom portion 1b of thechamber 1. To the exhausting port 8, an exhausting system 9 (a vacuumpump etc.) is connected. The atmosphere and a gas contained in thechamber 1 are exhausted outside by the exhausting system 9. As a result,the pressure is reduced to obtain a predetermined degree of vacuum.

A shower head 10 for supplying a process gas (described later) isprovided on the upper cover 1a of the chamber 1. The shower head 10 isconstituted of three blocks, namely, upper block 10a, middle block 10b,and the lower block 10c, which are integrated into one body in thevertical direction.

In the upper surface of the upper block 10a, an Al raw material inlet 11and a Cu raw material inlet 12 are provided. The Al raw material inlet11 is used for introducing an Al raw material from a Al raw materialsupply system 20 (described later). The Cu raw material inlet 12 is usedfor introducing a Cu raw material from a Cu raw material supply system40 (described later). A pipe extending from the Al raw material inlet 11is branched into a plurality of Al raw material passages 13 inside theupper block 10a. Each of the branched Al raw material passages 13 iscommunicated with an Al raw material passage 15 formed in the middleblock 10b, and further connected to an Al raw material gas-ejectingorifice 17 in the lower block 10c.

On the other hand, a pipe is arranged extending from the Cu raw materialinlet 12 but it is not communicated with Al raw material inlet 11, theAl raw material passage 13, and Al raw material gas-ejecting orifice 17.More specifically, the pipe extending from the Cu raw material inlet 12is branched into a plurality of Cu raw material passages 14 inside theupper block 10a. Each of the Cu raw material passages 14 is communicatedwith a Cu raw material passage 16 formed in the middle block 10b, andfurther connected to a Cu raw material gas-ejecting orifice 18 in thelower block 10c.

As described above, the shower head 10 has the Al raw material supplyroute and the Cu raw material supply route which are completelyindependent of each other. The Al and Cu raw material gas-ejectingorifices 17 and 18 are arranged alternately at predetermined intervals.Furthermore, a cooling water passage is formed in the shower head 10. Acooling water is supplied from a water inlet pipe 19 and circulatethrough the shower head 10, thereby controlling temperature thereof.

The chamber 1 has a transporting system (not shown) for transporting asemiconductor wafer W to the susceptor 2 and has a load-and-unload rockchamber (not shown) for loading and unloading the semiconductor wafer Winto and out of the chamber 1.

Now, the Al raw material supply system 20 will be explained withreference to FIG. 2.

The Al raw material supply system 20 has an Al raw material supply line21 and an Al raw material vessel 22. The Al raw material supply line 21is connected to the Al raw material inlet 11 of the shower head 10 andresponsible for supplying an Al raw material. The Al raw material vessel22 is filled with an Al raw material such as dimethylaluminium hydride(DMAH). The vessel 22 may be heated.

The Al raw material supply system 20 further comprises a bubbling line25, a purge line 32, and a bypass line 36. The bubbling line 25 suppliesa carrier gas such as H₂ gas into the Al raw material vessel 22 tobubble DMAH. Since DMAH is a liquid form at normal temperature, it isgasified by the bubbling operation. The purge line 32 is responsible notonly for purging the raw material gas remaining in the Al raw materialsupply line 21 and in the chamber 1 but also for controlling an innerpressure of the chamber 1 by introducing a gas into the chamber beforethe raw material gas is supplied. The bypass line 36 is branched fromthe bubbling line 25 and the purge line 32 and plays a role inexhausting the raw material gas to prevent the raw material gas frombeing supplied to the apparatus.

The Al raw material supply line 21 is constituted of a valve 26, switchvalves 28, 29 and a pipe connecting the elements mentioned. An end ofthe Al raw material supply line is inserted into the Al raw materialvessel 22 but not in contact with the Al raw material. The other endthereof is connected to the Al raw material inlet 11 of the shower head10. The valve 26 plays a role in initiating and terminating the rawmaterial gas supply. The switch valve 28 is responsible for switching agas flow to a branched bypass line 36. The switch valve 29 isresponsible for switching the gas flow to a branched purge line.

To prevent the gasified raw material from returning to a liquid form,the Al raw material vessel 22 is maintained at, e.g., 25° C. and the gassupply pipe of the Al raw material supply line 21 is maintained at e.g.,35° C.

The bubbling line 25 is constituted of a gas source 24, a valve 30, amass-flow controller 27, a switch valve 31, and a pipe connecting theelements mentioned. As the gas source 24, use may be made of, forexample, a gas cylinder which is filled with a carrier gas (H₂) for usein bubbling. The valve 30 is responsible for initiating and terminatingthe carrier-gas supply. The mass-flow controller 27 is responsible forcontrolling the flow rate of the Al raw material gas, which is generatedby controlling a flow rate of the carrier gas. The switch valve 31 playsa role in switching the gas flow from a main pipe to a branched bypassline 36. The open end of the gas pipe is inserted into DMAH contained inthe Al raw material vessel 22.

It is preferable that the same type of gas should be used as the purgegas (to be supplied to the purge line 32) and as the carrier gas for usein bubbling. For example, H₂ gas is preferable.

The purge line 32 is constituted of a purge gas source 33, a valve 34, amass-flow controller 35, and a pipe connecting the elements mentioned.An end of the purge line 32 is connected to the switching valve 29. Asthe purge gas source 33, use may be made of a gas cylinder which isfilled with H₂ gas. The valve 34 is responsible for initiating andterminating the carrier-gas supply. The mass-flow controller 35 plays arole in controlling the flow rate of the purge gas.

The bypass line 36 is constituted of a pipe line branched from theswitching valve 28 of the Al raw material supply line 21 and a pipe linebranched from the switching valve 31 of the bubbling line 25, and thebranched lines are merged into an exhausting pipe, which is furtherconnected to the evacuation system.

Now, the Cu raw material supply system 40 will be explained withreference to FIG. 3.

The Cu raw material supply system 40 has a Cu raw material supply line41 and a Cu raw material vessel 42. The Cu raw material supply line 41is connected to the Cu raw material inlet 12 of the shower head 10 andresponsible for supplying the Cu raw material. The Cu raw materialvessel 42 is filled with a Cu raw material such ascyclopentadienylcoppertriethylphosphine (CpCuTEP). Since CpCuTEP is asolid material, CpCuTEP is coated over a plurality of spherical bodies,which are accommodated in the Cu raw material vessel 42 in thisembodiment.

Furthermore, since CpCuTEP is present in a solid form at normaltemperature, a heater is provided in the Cu raw material vessel 42 toheat CpCuTEP. The Cu raw material supply system is constituted of agasification line 45, a purge line 52, and a bypass line 56. Thegasification line 45 plays a role in introducing H₂ gas into the vessel42 to gasify CpCuTEP, thereby producing the Cu raw material gas. Thepurge line is responsible not only for purging the raw material gas leftin the Cu raw material supply line 41 and in the chamber 1 but also forintroducing a gas before the raw material gas is introduced into thechamber 1 to control the inner pressure thereof. The bypass line 56 isbranched from the gasification line 45 and the purge line 52, and playsa role in exhausting the raw material gas to prevent the raw materialgas from being supplied to the apparatus.

The Cu raw material supply line 41, one end of which is inserted intothe Cu raw material contained in the Cu raw material vessel 42, and theother end of which is connected to the Cu raw material inlet 12 of theshower head 10. The Cu raw material supply line 41 is constituted of avalve 46, switching valves 48, 49, and a pipe connecting the elementsmentioned. The valve 46 is responsible for initiating and terminatingthe Cu raw material supply. The switching valves 48 and 49 play a rolein switching the flow into a branched bypass line 56 and a branchedpurge line 52, respectively.

Note that a heater 58 is provided in the periphery of the Cu rawmaterial supply line 41, extending from the Cu raw material vessel 42 tothe chamber 1. The Cu raw material supply line 41 is heated by theheater 58 to a predetermined temperature, e.g., 75° C. On the otherhand, a heater 59 is provided in the periphery of the carrier gas pipe45. The gas pipe 45 is heated to a predetermined temperature, e.g., 65°C. Furthermore, the Cu raw material vessel 43 is heated by a heater 60to a predetermined temperature, e.g., 65° C.

The gasification line 45 is constituted of a gas supply source 44, avalve 50, a mass flow controller 47, a switch valve 51, and a pipeconnecting the elements mentioned. As the gas supply source 44, use maybe made of, for example, a gas cylinder which is filled with a carriergas (H₂). The valve 50 is responsible for initiating and terminating thecarrier gas supply. The mass-flow controller 47 controls a flow rate ofthe raw material gas, which is generated by controlling a flow rate ofthe carrier gas. The switching valve 51 plays a role in switching theflow into the branched bypass line 56. The open end of the gasificationline 45 is inserted into the Cu raw material vessel 42 but not incontact with the Cu raw material.

The purge line 52 is constituted of a purge gas source 53, a valve 54, amass-flow controller 55, and a pipe connecting the elements mentioned.As the purge gas source 53, use may be made of, for example, a gascylinder which is filled with gas (H₂). The valve 54 is responsible forinitiating and terminating purge gas supply. The mass-flow controllerplays a role in detecting a flow rate of the purge gas. The purge line52 is connected to the switching valve 49.

It is preferable that the same type of gas should be used as the purgegas (to be supplied to the purge line 52) and as the carrier gas for usein bubbling. For example, H₂ gas is preferable.

The bypass line 56 is constituted of a pipe line branched from theswitching valve 48 of the Cu raw material supply line 41 and a pipe linebranched from the switching valve 51 of the bubbling line 45, and thebranched lines are merged into the exhausting pipe which is furtherconnected to the evacuation system 9.

In the CVD apparatus having the Al raw material supply system 20 and theCu raw material supply system 40, an Al raw material gas (DMAH) issupplied into the chamber 1 from the Al raw material supply line 21 whenan Al film is formed. At this time, the switching valve 48 is opened andthe switching valve 49 is closed. By virtue of these operation, the Curaw material gas is led into a branched bypass line 56 and exhaustedfrom the exhausting system 9. The Cu raw material gas is thereforesuccessfully prevented from being introduced into the chamber 1.

When the Cu film is formed, the Cu raw material gas (CpCuTEP) issupplied from the Cu raw material supply line 41 to the chamber 1. Atthis time, the switching valve 28 is opened and the switching valve 29is closed. By virtue of these operations, the Al raw material gas is ledinto the branched bypass line 36 and exhausted from the exhaustingsystem 9. The Al raw material gas is therefore successfully preventedfrom being introduced into the chamber 1.

Next, we will explain the method of forming an Al/Cu multilayered filmby using the CVD apparatus according to this embodiment.

The chamber 1 (under atmospheric pressure) is drawn by a vacuum pumpthrough the exhausting system 9 to obtain a highly-vacuumed state. Whilethis state is maintained, a semiconductor wafer W having a TiN filmformed on the substrate surface is loaded into the chamber 1 from theloadlock chamber (not shown) and set on the susceptor 2. Then, thesemiconductor wafer W is heated to 190° C. by the heater 5 embedded inthe susceptor 2.

Subsequently, H₂ gas is introduced into the chamber 1 from both oreither of the purge gas sources 33, 53 at a flow rate of, e.g, 1000SCCM, by operating the switch valves 29 and 49. As a result, the degreeof vacuum of the chamber 1 is adjusted at, e.g, 5 Torr.

At the same time, H₂ gas is supplied into the bypass lines 36, 56 at aflow rate of 1000 SCCM from the gas supply sources 24, 44 by operatingthe switching valves 31, 51, 28 and 48.

At this time, pressures inside the pipe lines upstream of pressurecontrollers (not shown), which are respectively fitted on the Al rawmaterial supply line 21 and the Cu raw material supply line 41, arecontrolled equal to those of the raw material vessels 22 and 42 by meansof the pressure controllers.

In this case, the pressure of the Al raw material vessel 22 is set at,e.g., 100 Torr. The pressure of the Cu raw material vessel 42 is set at,e.g., 160 Torr.

After the pressure is stabilized, the carrier gas is supplied into theAl raw material vessel 22 and the Cu raw material vessel 42 from thebypass lines 36, 56 respectively by operating the switch valves 31, 51.

DMAH (Al raw material) is bubbled and gasified by the aforementionedoperation. The gasified DMAH is sent to the Al raw material supply line21 together with a carrier gas (H₂). The DMAH flow is switched into thebranched bypass line 36 by the operation of the switch valve 28. In thismanner, DMAH is exhausted from the bypass line 36. In the same manner,CpCuTEP (Cu raw material) is gasified and sent to the Cu raw materialsupply line 41 together with the carrier gas (H₂). The CpCuTEP flow isswitched into the branched bypass line 56 by the operation of the switchvalve 48, and then exhausted.

When a chamber pressure is stabilized and temperature of thesemiconductor wafer reaches a predetermined value, the raw material gasis supplied into the chamber 1 by operating either switch valves 28 and29 or switch valves 48 and 49. In this way, film formation is started.The Al film may be formed first or the Cu film may be formed first.

Now, we will explain the case where the Cu film is formed after the Alfilm is formed in accordance with the aforementioned process. When thefilm is formed, temperature of the wall portion of the chamber 1 is setat, e.g., 50° C. to prevent an extra film from being deposited.

By virtue of the aforementioned operation, the carrier gas is suppliedinto the chamber 1 via the switch valve 29 and the Al raw material gasis supplied into the branched bypass line 36. Similarly, the Cu rawmaterial gas is supplied into the bypass line 56 via the switch valve48.

While the supply of the H₂ gas into the chamber 1 i s terminated byoperating switch valves 28 and 29, the Al raw material gas (DMAH+H₂)flowing into the bypass line 36 is then changed to flow into thechamber 1. The Cu raw material gas (CpCuTEP+H₂) is supplied into thebypass line 56.

At that time, a flow rate of the H₂ gas (carrier gas) is set at, e.g.,1000 SCCM. An inner pressure and temperature of the Al raw materialvessel 22 are set at about 100 Torr and about 65° C., respectively.Temperature of the Al raw material supply line 21 is set at, e.g., 35°C.

In this way, a first Al film is formed on the semiconductor wafer W 45.

A predetermined time after the first Al film is formed in apredetermined thickness, the switch valve 28 is operated. The Al rawmaterial gas flowing into the chamber 1 through the Al raw materialsupply line 21 is switched to flow into the bypass line 36. In thismanner, the Al raw material gas is exhausted.

Thereafter, the switch valve 48 is operated to supply the Cu rawmaterial gas, which has been supplied to the bypass line 56, into thechamber 1.

The switch valves 28 and 48 may be operated either simultaneously orseparately. To be more specific, after the Al raw material gas flow isswitched to the bypass line 36, the Cu raw material gas may be suppliedinto the chamber 1. Note that if the Al raw material gas is co-presentwith the Cu raw material gas in the chamber 1, the gases may react witheach other and generate a reaction product. To prevent the reaction, itis preferred to employ either a method in which the chamber 1 is purgedwith H₂ gas supplied from the purge gas source 33 after the Al rawmaterial gas flow is switched to the bypass line 36, or a method inwhich after the Al raw material gas is exhausted by a vacuum pump, theCu raw material gas is supplied into the chamber 1. In the opposite casewhere the Cu raw material gas is supplied before the Al raw materialgas, the switching operation of the supplied gas may be carried out inthe similar manner.

When the Cu raw material gas is supplied in place of the Al raw materialgas, H₂ gas (carrier gas) is supplied at a flow rate of e.g., 1000 SCCM.Inner pressure and temperature of the Cu raw material vessel 42 are setat about 100 Torr and about 65° C., respectively. Temperature of thegasification line 45 is set at about 65° C. Temperature of the Cu rawmaterial supply line 41 is set at about 75° C.

After a first Cu film is formed on the first Al film in a desiredthickness under these conditions, the Cu raw material gas is suppliedinto the bypass line 56 by the operation of the switch valve 48. In thisway, the Cu film formation step is terminated.

Then, to form a second Al film, the Al raw material gas is supplied intothe chamber 1 switching from the bypass line 36 by the operation of theswitch valve 28. In this way, the second Al film is formed on the firstCu film.

If the aforementioned operations are repeatedly performed, it ispossible to form Al/Cu multilayered film in which the Al film and Cufilm are alternately stacked in a desired layer-number.

When a series of film-formation processes is terminated, the valves 30,50 are first operated to stop the carrier gas. Then, switch valves 31,51 are operated to exhaust the carrier gas left in the pipe.

Thereafter, the chamber 1 is drawn by a vacuum pump to a high degree ofvacuum, thereby exhausting the remaining gas. Alternatively, the chamber1 may be drawn by a vacuum pump after post flow is performed for apredetermined time period by introducing H₂ gas into the chamber 1 fromthe purge gas sources 33, 53 and terminating the H₂ gas supply by theoperation of the switch valves 29, 49.

The Al/Cu multilayered film thus formed on the semiconductor wafer W issubjected to an annealing step under predetermined conditions. Theannealing treatment induces diffusion between the Al film and the Cufilm. As a result, a desired Al/Cu alloy film is formed.

The multilayered film is formed under the typical film formationconditions below.

First, the substrate is heated to 190° C. and inner pressure of thechamber 1 is set at 5 Torr. Then, the Al raw material (DMAH) is suppliedtogether with H₂ gas (carrier gas) at a flow rate of 1000 SCCM for 234seconds by use of a bubbler (Step (1)). The pressure at an outlet of thebubbler is 100 Torr and a vapor pressure of DMAH at room temperature isabout 2 Torr. Thereafter, H₂ gas serving as a purge gas is supplied at aflow rate of 1000 SCCM for 20 seconds (Step (2)), and then, CpCuTEP gas(Cu raw material gas) set at 80° C., 100 Torr, is supplied for 60seconds together with H₂ carrier gas (Step (3)). Subsequently, H₂ purgegas is supplied for 20 seconds at 1000 SCCM (Step (4)). A series ofsteps (1) to (4) is repeated 7 times. In this manner, an Al/Cumultilayered film having an overall thickness of 25,000 Å is formed. Theobtained multilayered film is then subjected to an annealing stepperformed at 40° C. for 30 minutes under an hydrogen atmosphere. As aresult, an Al/Cu alloy film is obtained.

In the case where the alloy film is formed from the multilayered film inwhich the Al film and the Cu film are stacked one upon the other aplurality of times, it is generally preferable that a single film shouldbe formed in a thickness of about 2000 Å or less. In view of smoothnessof each film, it is preferred to set the thickness of the single film atabout 500 Å; however, the film formation step is inevitably repeatedmore. This means that the throughput decreases. Hence, most preferably,the thickness of the single film is within the range of 1000 to 2000 Å.

As explained in the foregoing, according to the CVD apparatus of thisembodiment, it is possible to form the Al/Cu multilayered film in asingle chamber. This is because the Al film (made of the Al raw materialgas) and the Cu film (made of the Cu raw material gas) can be formedindependently and alternately in the same chamber. Hence, the Al/Cumultilayered film is formed with a high throughput and withoutincreasing the size of the manufacturing apparatus.

The Al raw material supply line and Cu raw material supply line areindependently connected to the shower head, passed through the showerhead without merging, and connected to the chamber. Hence, there islittle possibility for the Al raw material to react with the Cu rawmaterial.

Furthermore, there are provided a first bypass line (for exhausting theAl raw material gas) and a second bypass line (for exhausting the Cu rawmaterial gas) bypassing the chamber. Hence, when the Al raw material gasis introduced into the chamber through the Al raw material supply line,the Cu raw material gas is introduced into the second bypass line.Whereas, when the Cu raw material gas is introduced into the chamberthrough the Cu raw material supply line, the Al raw material gas isintroduced into the first bypass line. In this way, it is possible toprevent the reaction between the Al raw material and the Cu rawmaterial.

In this embodiment, since the aforementioned materials are chosen as rawmaterials, both Al film and Cu film may be formed on the semiconductorwafer W set at the same temperature. Therefore, while the susceptor iskept at the same temperature by the heater, the films can be formedcontinuously. It is therefore possible to increase the throughput.

Note that the present invention is not limited to the aforementionedembodiments and may be modified in various ways. In the embodiments, theraw materials gases are supplied from raw material supply orificesarranged in a matrix shower form in the head shower which is positionedin the upper portion of the chamber. However, the supply means for theraw materials is not limited to this. Any supply means may be used aslong as the Al raw material and Cu raw material can be suppliedindependently. For example, use may be made of two ring-form supplymeans having numerous gas spurting-out holes.

Furthermore, it is not necessary to use a bubbling scheme to gasify theraw material. A predetermined amount of a liquid material may bedirectly gasified by using a liquid mass-flow controller. The carriergas and the purge gas are not limited to H₂ gas. An inert gas such as Armay be used.

Now, we will explain an modified embodiment of the Cu raw materialsupply system 40 with reference to FIG. 4. In the aforementioned Cu rawmaterial supply system 40, cyclopentadienylcopperethylphosphine(CpCuTEP) is employed, whereas, a liquid Cu material is used in the Curaw material supply system of the modified embodiment.

A Cu raw material vessel of the modified embodiment differs in structurefrom that shown in FIG. 3. Like reference numerals are used to designatelike structural elements corresponding to those in FIG. 3 and anyfurther explanation is omitted for brevity's sake.

As the liquid Cu raw material,hexafluoroacetylacetonatetrymethylvinylsilylcopper (hfacCuVTMS) 62 isused.

Liquid-form hfacCuVTMS 62 contained in a Cu raw material vessel 61 isgasified by bubbling and supplied to a Cu raw material supply line 41 inthe same manner as in the Al raw material supply system 20. H₂ gasserving as the carrier gas for use in bubbling is supplied from a gassupply source 44 through a carrier gas pipe 45 to the Al raw amterialvessel 61. Upon supplying H₂ gas, hfacCuVTMS 62 is bubbled andpressure-supplied through the pipe 41 into the chamber 1.

As the Al raw material and the Cu raw material, the aforementionedcombinaiton is preferable. However, they are not limitd to theaforementioned combination. Various combinations may be employed.

For example, as the Al raw material, there are triisobutylaluminium(TIBA), dimethylethylaminoalane (DMEAA), trimethylaminealane (TMAA),trimethylaluminium (TMA) and the like.

As the Cu raw material, there arecyclopentadienylcoppertrimethylphosphine (CpCuTMP),cyclopentadienylcoppertriisopropylphosphine (CpCuTIPP),ethylcyclopentadienylcoppertriethylphosphine (EtCpCuTEP) and the like.

Furthermore, conditions including temeperature, pressure at the time ofthe film-formation may be appropriately set depending upon a film to beobtained.

In this embodiment, the Al film is first formed on the semiconductorsubstrate and then the Cu film is formed. However, the Cu film may beformed first before the Al film.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A CVD (chemical vapor deposition) apparatus,comprising:a chamber configured to maintain vacuum conditions having anexhausting system; a susceptor disposed in the chamber, configured tomount an object to be processed; an exhausting system configured tovacuum-exhaust an atmosphere of the chamber including a gasified rawmaterial introduced thereinto; an Al raw material supply system havingan Al raw material supply line configured to introduce a gasified Al rawmaterial into the chamber, in order to form an Al film; said Al rawmaterial supply system comprising; an Al raw material gas generatingdevice having the Al raw material supply line for supplying an Algaseous raw material and a vessel to which a liquid-state Al rawmaterial is to be loaded, and configured to generate an Al raw materialgas by bubbling with a carrier gas and introduce the Al raw material gasinto the chamber; an Al gas bypass device configured to either supplythe generated Al raw material gas to the chamber or to exhaust thegenerated Al raw material gas outside using the exhausting device byswitching a valve; a first gas purge device configured to purge aremaining gas in the chamber or in a gas pipe by supplying a carrier gaseither from the Al raw material gas supply line to the chamber or fromthe Al raw material supply line to the Al raw material gas bypassdevice; and an Al raw material switch configured to switch eitherbetween the Al raw material gas bypass device and the Al raw materialsupply line or between the first gas purge device and the Al rawmaterial supply line; and a Cu raw material supply system having a Curaw material supply line configured to introduce a gasified Cu rawmaterial supply line configured to introduce a gasified Cu raw materialinto the chamber, in order to form a Cu film, said Cu raw materialsupply line being independent of said Al raw material supply line; saidCu raw material supply system comprising: a Cu raw material gasgenerating device having the Cu raw material supply line for supplying aCu gaseous raw material and a vessel to which a solid-state Cu rawmaterial is to be loaded, and configured to generate a Cu raw materialgas by heating to vaporize the Cu raw material and to introduce the Curaw material gas into the chamber; an Cu gas bypass device configured toeither supply the generated Cu raw material gas to the chamber or toexhaust the generated Cu raw material gas outside using the exhaustingdevice by switching a valve; a second gas purge device configured topurge a remaining gas in the chamber or in a gas pipe by supplying acarrier gas either from the Cu raw material gas supply line to thechamber or from the Cu raw material supply line to the Cu raw materialgas bypass device; and an Cu raw material switch configured to switcheither between the Cu raw material gas bypass device and the Cu rawmaterial supply line or between the first gas purge device and the Curaw material supply line, wherein the Al film, formed of the Al rawmaterial gas, and the Cu film, formed of the Cu raw material gas, arealternately stacked one upon the other by chemical vapor deposition(CVD) on a surface of the object mounted on the susceptor by introducingthe Al raw material gas or the Cu raw material gas alternately.
 2. TheCVD apparatus according to claim 1, whereina Cu raw material gas flowroute and an Al raw material gas flow route are switched to each otherby operating the Cu raw material gas switch and the Al raw material gasswitch in such a manner that in the case where the Al raw material gasproduced by the Al raw material gas generating device is introduced intothe chamber through the Al raw material supply line, the Cu raw materialgas produced by the Cu raw material generating device is exhausted bythe exhaust device through the Cu raw material gas bypass device; or inthe case where the Cu raw material gas produced by the Cu raw materialgas generating device is introduced into the chamber through the Cu rawmaterial supply line, the Al raw material gas produced by the Al rawmaterial generating device is exhausted by the exhaust device throughthe Al raw material gas bypass device, said cases being controlled byoperation of the Cu raw material gas switch and Al raw material gasswitch.
 3. A CVD apparatus comprising:a chamber configured to maintainvacuum conditions having an exhausting system; a susceptor disposed inthe chamber, configured to mount an object to be processed; an Al rawmaterial supply system having an Al raw material supply line configuredto introduce a gasified Al raw material into the chamber, in order toform an Al film; a Cu raw material supply system having a Cu rawmaterial supply line configured to introduce a gasified Cu raw materialinto the chamber, in order to form an Al film, said Cu raw materialsupply line being independent of the Al raw material supply line of theAl raw material supply system; an exhausting system configured tovacuum-exhaust an atmosphere of the chamber including a gasified rawmaterial introduced thereinto; a bypass device connected between the Alraw material supply line and the exhaust device and between the Cu rawmaterial supply line and the exhaust device and between the Cu rawmaterial supply line and the exhaust device, and configured to evacuatethe Al raw material gas and the Cu raw material gas and the Cu rawmaterial gas to be supplied by the exhaust device without beingintroduced into the chamber; and a switch device consisting of switchvalves respectively attached onto the Al raw material supply line andthe Cu raw material supply line, connected to the bypass device, andconfigured to supply either the Al raw material gas or the Cu rawmaterial gas, wherein in the case where the Al raw material gas producedby the Al raw material gas generating device is introduced into thechamber through the Al raw material supply line, the Cu raw material gasis exhausted by the exhaust device through the Cu raw material gasbypass device; or in the case where the Cu raw material gas produced bythe Cu raw material gas generating device is introduced into the chamberthrough the Cu raw material supply line, the Al raw material gas isexhausted by the exhaust device through the Al raw material gas bypassdevice, said cases being controlled by operation of the Cu raw materialgas switch device and Al raw material gas switch device, the Al film,formed of the Al raw material gas, and the Cu film, formed of the Cu rawmaterial gas, are alternately stacked one upon the other by chemicalvapor deposition (CVD) on a surface of the object mounted on thesusceptor by introducing either the Al raw material gas or the Cu rawmaterial gas.
 4. The CVD apparatus according to claim 3, wherein the Curaw material generating device generates a Cu raw material gas from asolid-state Cu raw material contained in a vessel by heating.